Python charmhelpers.core.host 模块，CompareHostReleases() 实例源码

def memcache(self):
        ctxt = {}
        ctxt['use_memcache'] = False
        if self.charm_instance:
            if (ch_utils.OPENSTACK_RELEASES.index(
                    self.charm_instance.release) >=
                    ch_utils.OPENSTACK_RELEASES.index('mitaka')):
                ctxt['use_memcache'] = True

        if ctxt['use_memcache']:
            # Trusty version of memcached does not support ::1 as a listen
            # address so use host file entry instead
            release = ch_host.lsb_release()['DISTRIB_CODENAME'].lower()
            if ch_ip.is_ipv6_disabled():
                if ch_host.CompareHostReleases(release) > 'trusty':
                    ctxt['memcache_server'] = '127.0.0.1'
                else:
                    ctxt['memcache_server'] = 'localhost'
                ctxt['memcache_server_formatted'] = '127.0.0.1'
                ctxt['memcache_port'] = '11211'
                ctxt['memcache_url'] = '{}:{}'.format(
                    ctxt['memcache_server_formatted'],
                    ctxt['memcache_port'])
            else:
                if ch_host.CompareHostReleases(release) > 'trusty':
                    ctxt['memcache_server'] = '::1'
                else:
                    ctxt['memcache_server'] = 'ip6-localhost'
                ctxt['memcache_server_formatted'] = '[::1]'
                ctxt['memcache_port'] = '11211'
                ctxt['memcache_url'] = 'inet6:{}:{}'.format(
                    ctxt['memcache_server_formatted'],
                    ctxt['memcache_port'])
        return ctxt

def test_compare_ubuntu_releases(self):
        from charmhelpers.osplatform import get_platform
        if get_platform() == 'ubuntu':
            self.assertTrue(host.CompareHostReleases('yakkety') < 'zesty')